package com.mingdong.first.danli;

public class DoubleIfSingleton {

	private DoubleIfSingleton(){
		
	}
	private static volatile DoubleIfSingleton instance = null;
	
	public static DoubleIfSingleton  getInstance(){
		
		if(instance == null){			

			synchronized (DoubleIfSingleton.class) {
				if(instance == null){
				instance = new DoubleIfSingleton();
				}
			}			
		}
		return instance;
	}
	
}
